The primary aim of this second resubmission is to evaluate the efficacy of Parent Management Training (PMT) and a relatively new Cognitive Behavior Therapy, Collaborative Problem Solving (CPS), in the treatment of 150 children between 8 and 12 years of age who are diagnosed with Oppositional Defiant Disorder (ODD). Children and their parents will be randomly assigned to PMT, CPS, or wait list control conditions. The current proposal will evaluate these children prior to treatment, throughout treatment, immediately following treatment, and 1 year thereafter. The secondary aim is to examine the predictors of durable gains associated with treatment. Research suggests a matrix of predictor variables worthy of investigation including child sociodemographics, severity of the disorder, comorbidity with other disorders, parental psychopathology, and family functioning. These potential predictors of treatment outcome will be obtained before treatment begins to determine their utility in the prediction of treatment outcome. Identification of these predictors might constitute the first step in determining which children with which characteristics respond best to treatment and which ones do not. Some of these predictors might function as moderators of treatment outcomes whereas others might serve as "nonspecific" predictors of treatment outcome. It is possible that such findings might also lead to enhanced treatment outcomes by altering treatments to address certain characteristics associated with change. The tertiary aim is to investigate various treatment mechanisms (mediating variables) thought to be associated with treatment outcomes. The identification of such variables is necessary in order to understand how treatments such as PMT and CPS actually work. Specifically we hope to examine changes in parenting practices as a mediator of PMT and changes in parent-child problem solving as a mediator of CPS. ODD is a childhood disorder that is characterized by a recurrent pattern of developmentally inappropriate levels of negativistic, defiant, disobedient, and hostile behavior toward authority figures, and is estimated to occur in 2 to 16 percent of children. Behaviors associated with ODD include temper outbursts;persistent stubbornness;resistance to directions;unwillingness to compromise, give in, or negotiate with adults or peers;deliberate or persistent testing of limits;and verbal (and minor physical) aggression. Parents of children with ODD are more likely to utilize child mental health services than parents of children with other behavior disorders, presumably due to the deleterious effects of ODD-related behaviors on interactions between children and their adult caretakers. Studies have shown that ODD, independent of its association with attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD), is a highly comorbid disorder with adverse effects on children's social and family functioning and long-term outcomes. Given its adverse outcomes the pursuit of treatments that work, both in the short-term and the long-term, are desired.